1. Technical Field
The present invention relates to an imaging device, an imaging method and an imaging program in which an imaging element produces image data on the basis of light received from an object.
2. Related Art
Digital still cameras (shortened as DSC, hereafter) have come into wide use in recent years, and are often used in place of photographic film cameras. Professional photographers and experienced amateurs, however, are not satisfied with DSCs in lots of respects, and the DSC has not fully taken over for film cameras. Thus, the DSC is still being refined so as to meet such user's demands. One of such refinements is to provide a function for magnifying and displaying a portion of a through-the-lens image, so as to solve a problem caused by a low resolution performance of a display for displaying the through-the-lens image in that the extent to which the image is in focus on the display cannot be ensured, as disclosed in JP-A-2006-222979 and JP-A-2005-328225. For example, when photographing a person in a full-body shot, the person's face may be magnified on the display screen, blocking a portion of the background. While the expanded image is displayed on the display screen or electronic viewfinder, hitting the shutter button captures the entire, unmodified image.
Another problem of the DSC is delay time in various processes after an object is photographed by means of an imaging element and until a through-the-lens image is displayed.
FIG. 3B illustrates a time lag between a truly recorded image and a preview image after and before a shutter of an ordinary DSC is released. As illustrated in FIG. 3B, an imaging element, a Video Random Access Memory (VRAM) and a display of an imaging device cause a “reading delay”, a “writing delay” and a “display delay”, respectively. The “reading delay” is a period of time required after completion of exposure of the imaging element and before completion of output of signal electric charges of the imaging element. The “writing delay” is a period of time required for image data of one screen on the display to be written to the VRAM. The “display delay” is a period of time required for an image of one screen to be displayed on the display.
An imaging element of a frame rate of, e.g., 60 frames per second (fps) may cause a “reading delay” of nearly 16.7 ms in some cases. Further, an image displayed in accordance with the National Television System Committee (NTSC) standard is subjected to a “display delay” of nearly 33.3 ms per one screen as the frame rate is nearly 30 fps. Further, the VRAM causes a “writing delay” according to its writing speed, though this is much smaller than the “reading delay” or the “display delay” at present. Thus, when a user releases the shutter while viewing the preview screen in those cases, it is supposed that a delay of at least 50.0 ms has already been caused. In addition, an “imaging process delay” is caused as well, as the DSC carries out a process preparatory to imaging. In those circumstances, it is difficult for an ordinary DSC to photograph an object at the precise instant desired by the user, possibly resulting in failure to photograph the object.